Schizophrenia is the most common type of psychosis caused by an excessive neurotransmission activity of the dopaminergic nervous system in the central nervous system. A number of drugs have been developed having the activity to block the neurotransmission of dopaminergic receptor in the central nervous system. For example, among the drugs developed are phenothiazine-type compounds such as chlorpromazine; butyrophenone-type compounds such as haloperidol; and benzamide-type compounds such as sulpiride. The drugs are used to improve so-called positive symptoms in the acute period of schizophrenia such as hallucinations, delusions, excitations, and the like. Many drugs for treating schizophrenia, however, are not effective for improving the so-called negative symptoms which are observed in the chronic period of schizophrenia such as apathy, emotional depression, hypopsychosis, and the like. The drugs currently used have produced undesired side effects such as akathisia, dystonia, Parkinsonism dyskinesia, and late dyskinesia, which are caused by blocking the neurotransmission of dopaminergic receptor in the striate body.
Aripiprazole is a pyschotropic drug that exhibits high affinity for dopamine D2 and D3, serotonin 5-HT1A and 5-HT2A receptors, moderate affinity for dopamine D4, serotonin 5-HT2C and 5-HT7, α1-adrenergic and histamine H1 receptors, and moderate affinity for the serotonin reuptake site. Also, aripiprazole has no appreciable affinity for cholinergic muscarinic receptors. The mechanism of action of aripiprazole, as with other drugs having efficacy in schizophrenia, is unknown. It has been proposed, however, that the efficacy of aripiprazole is mediated through a combination of partial agonist activity at D2 and 5-HT1A receptors and antagonist activity at 5-HT2A receptors. Drugs effective for improving the negative symptoms and effective for improving the positive symptoms of schizophrenia are still highly desirable, more so, when the drugs can diminish the undesirable side effects.
U.S. Pat. No. 5,006,528 provides a process for the preparation of BBQ in water in basic conditions. Water can often be difficult to remove from reaction mixtures. Accordingly, the present invention encompasses methods of synthesizing BBQ, an intermediate commonly used in the synthesis of aripiprazole, as aripiprazole is safer than other anti-psychotic drugs such as olanzapine or ziprazidone.